For an external pointer > xp <pointer: (nil)> one might expect all.equal to behave as for environments > e = new.env() > all.equal(e, e) [1] TRUE but it does not > all.equal(xp, xp) Error in unclass(target) : cannot unclass an external pointer A solution is to dispatch to all.equal.language (?) in src/library/base/R/all.equal.R:26 but this requires an is.expternalptr primitive. In some respects, one might expect all.equal for environments to be more thorough e = new.env(); e[["a"]] = 1 all.equal(e, new.env()) ## expect FALSE, as in next line all.equal(as.list(e), as.list(new.env())) all.equal(new.env(), new.env()) ## TRUE; ok? Martin -- Computational Biology / Fred Hutchinson Cancer Research Center 1100 Fairview Ave. N. PO Box 19024 Seattle, WA 98109 Location: Arnold Building M1 B861 Phone: (206) 667-2793